Sunday, August 23, 2009

Wasps in the Barn

I found this nice paper wasp nest built by some Polistes species in the barn. Here it is, attached to the roof sheathing just beside a rafter. The scene here is typical of what you might find in any wasp nest.

This is what struck me as interesting. Scattered along the rafter, sometimes several feet from the nest, are these groups of wasps that are associated with the nest, but seem to have no work duties to perform. When I think of social insects such as ants, bees and wasps, I picture each individual hard at work doing some task that ultimately benefits the colony. I never imagined sitting around napping as one of those beneficial functions.

I thought at first that these wasps might be males waiting until they were needed to mate with the females that would overwinter to produce next year’s wasp colonies. A closer look showed the group to contain both male and female wasps. The male, with curled antennae and a yellow face, is shown on the left. On the right is the slightly larger, darker colored female.

Raised wings and head turned in your direction is a warning that you have invaded the wasp’s personal space and may receive more direct action if you don’t back off. This is a warning you should heed. Especially when you’re on the top a ladder with your head and shoulders stuck up through the ceiling joists.

A look down into some of the nest cells shows eggs and newly hatched larvae. The difference between an egg and a hatchling is the little black spot of a mouth on the upper end of the young larva. As more eggs hatch, those idle females will be needed to forage and care for the growing larvae. The males aren’t much for helping around the nest and will most likely maintain their lives of leisure.

1 comment:

  1. Great photos! Thanks for the info on how to tell male from female wasps. I'm always amazed at how persistent wasps are about coming back to a particular spot to build a nest.